This invention relates to a method for mounting a tire on a wheel with bead portions of the tire substantially uniformly fitted on the rim of the wheel and filling the tire with inner pressure.
In a conventional method for mounting a tire on a wheel, bead portions of the tire are first fitted on the rim of the wheel by the use of a tire-rim assembling apparatus, and the tire mounted on the wheel is subsequently filled with inner pressure by means of an air filling apparatus separate from the tire-rim assembling apparatus.
For example, a tire-rim assembling apparatus is disclosed in Japanese Utility Model Application Laid-open No. 50-104,302. In mounting a tire on a wheel with this prior art apparatus, the wheel is arranged on a table vertically movable and fixed thereat by means of an extensible and contractible center cone inserted into the hub hole formed in the center of the wheel. The tire is then arranged on the wheel in an inclined state so that a part of one bead portion of the tire is dropped into a well formed in one side region of the rim of the wheel. By rotating a swivel arm coaxially provided on the center cone, bead portions of the tire are expanded by guide rollers provided on the swivel arm and a side surface rubber of the tire is urged downwardly by restraining rollers vertically movably provided on the swivel arm. As a result, the bead portions of the tire are fitted one by one or simultaneously on the rim of the wheel.
On the other hand, an inner pressure filling apparatus is disclosed in Japanese Utility Model Application Laid-open No. 64-16,404, in which a side surface of a tire mounted on the rim of a wheel is urged downwardly by raising a table to form a filling opening between the bead portion of the tire and the wheel, through which opening pressurized air is filled within the tire. With this apparatus, pressurized air higher than the predetermined inner pressure must be applied into the tire for the purpose of supplementing the loss of the pressurized air due to its leakage from the tire caused by the lowering movement of the table.
In mounting the tire onto the rim by the use of the tire-rim assembling apparatus of the prior art, a portion of the bead portion not yet completely fitted on the rim is deformed straight like a chord relative to the annular flange of the rim shortly before the termination of the fitting operation. In this state, the guide rollers and the restraining rollers are further rolled so that the bead portion is expanded to be locally bent or curved and may be damaged as the case may be. Even if the bead portion of the tire is not damaged, the deformed bead portion detrimentally affects tire uniformity and sealing performance so that the inherent performance of the tire mounted on the rim could not be exhibited.
On the other hand, with the inner pressure filling apparatus of the prior art, the bead portions of the tire must instantaneously move or ride over the hump of the rim so as to be brought into contact with the rim. It is therefore required to supply pressurized air (4 to 6 kg/cm.sup.2) into the tire, which is higher than a set pressure (3 to 5 kg/cm.sup.2). Moreover, as the table is rapidly lowered in order to increase the efficiency of the inner pressure filling operation, the bead portions are abruptly urged against the flanges of the rim of the wheel. Therefore, it is difficult to assure uniform close contact between the bead portions of the tire and the flanges of the rim. Further, bead cores are likely to be deformed undesirably.
In addition thereto, a tire-rim assembling apparatus and an inner pressure filling apparatus must be separately provided in the prior art. Therefore, wide spaces are required for installing this apparatus.